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Why can some organisms (like planaria or salamanders) regenerate limbs, while others cannot? – Anna, age 12, Kansas City, Missouri

Why can some organisms (like planaria or salamanders) regenerate limbs, while others cannot? – Anna, age 12, Kansas City, Missouri

Imagine losing an arm and simply growing a new one. This amazing ability of regeneration isn’t just something from a superhero movie – it actually happens in real life for some animals.

Salamanders are known as champions of regeneration. If a salamander loses a leg, it can regrow another one, complete with bones, nerves, blood vessels and muscles.

Some fish are impressive regenerators too. Zebrafish – small, striped fish that scientists often use to study human diseases – can regenerate injured fins. Even more surprisingly, they can repair damaged parts of important organs such as their heart and brain.

Why can these animals regenerate while people cannot?

How regeneration works

If you suffer a severe injury, such as losing your hand, your body quickly works to close the wound and prevent infection. However, you cannot regenerate that lost hand. Instead, the wound heals and leaves a scar.

Regenerating animals respond differently to........

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